From seat 7A, I look down to see miles of dense rain forest blanketing the ground below me. Iím 10,000 feet above the Mexican state of Chiapas, coming in for a landing at Palenque, where an ancient Mesoamerican city flourished for five centuries, until its Mayan inhabitants mysteriously abandoned it, leaving their temples, homes and palaces to be reclaimed by the encroaching forest, not to be rediscovered for nearly 900 years.